The problem still persists for me as well. Same exact thing as Roland is experiencing, works fine in classic mode but not cinema mode (or through WMC). Hopefully the below information will help. Let me know if you need any additional information.
PowerDVD 10 Mark II Ultra Version 10.0.2916.51
SR Number: DVD110429-07
TR Number: TR110516-059
Windows 7 64-bit Service Pack 1
Administrator account
Downloaded version - upgraded from bundled product through Cyberlink
Nvidia GeForce GT 430
Latest driver 270.61
Toshiba 40" 1080p 120Hz LCD HDTV 40G300U
Connected by HDMI
Single monitor (TV)
I have 2 audio set ups that I can switch via Windows - one is to use the existing HDMI connection on the TV, the other is I have a Turtle Beach adapter that allows me to get optical audio to my Sony receiver/amplifier.
Microsoft Security Essentials installed
AnyDVD HD 6.8.0.0 used to rip Blu Rays and DVDs (installed on a different system)
Virtual CloneDrive 5.4.5.0